Infrared-sensitive lithographic printing plate

Abstract

There is provided an infrared-sensitive lithographic printing plate capable of direct plate-making based on digital data from a computer or the like, and excellent in development latitude and scratch resistance, which is an infrared-sensitive lithographic printing plate comprising a support and a heat-sensitive layer, the heat-sensitive layer comprising (A) a copolymer having a specific monomer unit having a carboxyl group, (B) an alkali-soluble high molecular weight compound having a sulfonamide group, and (C) a light-heat conversion material.

1. An infrared-sensitive lithographic printing plate comprising a support and a heat-sensitive layer, wherein the heat-sensitive layer comprises:
 (A) a copolymer having a monomer unit selected from the group consisting of monomer units represented by the following formulas, a-29, a-33, a-34, a-35 and a-36, and at least one monomer unit selected from the group consisting of (meth)acrylic acid esters and (meth)acrylamide derivatives: 
 
       
         
           
           
               
               
           
         
         (B) an alkali-soluble high molecular weight compound having a sulfonamide group; and 
         (C) a light-heat conversion material, 
         provided that the copolymer (A) and the compound (B) are separate and distinct components. 
       
     
     
       2. The infrared-sensitive lithographic printing plate according to  claim 1 , wherein the copolymer (A) comprises the monomer unit selected from the group consisting of monomer units represented by formulas, a-29, a-33, a-34, a-35 and a-36 in an amount of 1 to 90 mol%. 
     
     
       3. The infrared-sensitive lithographic printing plate according to  claim 1 , wherein the copolymer (A) further has at least one monomer unit which is a styrene derivative. 
     
     
       4. The infrared-sensitive lithographic printing plate according to  claim 3 , wherein the amount of the styrene derivative monomer unit is from 5 to 90 mol %. 
     
     
       5. The infrared-sensitive lithographic printing plate according to  claim 1 , wherein the amount of the at least one monomer unit selected from the group consisting of(meth)acrylic acid esters and (meth)acrylamide derivatives is from 5 to 90 mol%. 
     
     
       6. The infrared-sensitive lithographic printing plate according to  claim 1 , wherein the heat-sensitive layer comprises the copolymer (A) in an amount of 1 wt % to 40 wt %. 
     
     
       7. The infrared-sensitive lithographic printing plate according to  claim 1 , wherein the alkali-soluble high molecular weight compound (B) has at least one monomer unit of low molecular weight compounds each having in one molecule, at least one sulfonamide group —NH—SO 2 — and at least one polymerizable unsaturated bond. 
     
     
       8. The infrared-sensitive lithographic printing plate according to  claim 1 , wherein the heat-sensitive layer further comprises a novolak resin. 
     
     
       9. The infrared-sensitive lithographic printing plate according to  claim 1 , wherein the light-heat conversion material is an infrared absorbing dye. 
     
     
       10. The infrared-sensitive lithographic printing plate according to  claim 9 , wherein the infrared absorbing dye has an absorbance at 700 to 1200 nm infrared rays. 
     
     
       11. The infrared-sensitive lithographic printing plate according to  claim 1 , wherein the heat-sensitive layer comprises the light-heat conversion material in an amount of 0.01 to 50 wt %.